Denise Yazili knows just what to do when a customer in the fashion boutique where she works is unsure which item to buy.

“Look, this is what happens,” the shop assistant in an Istanbul mall said this week as she took a black sequined shirt from a rack and spread it out on the table before her.

“If the customer says she is looking for something Bihter wore and I tell her this is similar to what she was wearing last time, she will just snap it up.”

Bihter Yoreoglu, played by the actress Beren Saat, is one of the main characters of Ask-I Memnu, or Forbidden Love, a hit soap opera on Turkish television that has attracted millions of viewers and triggered its own fashion craze since it started two years ago.

The final episode of the saga will be aired today, and Turkish media and fan websites are abuzz with speculation about what the dramatic conclusion may be.

Dresses worn by the main characters, and especially by Bihter, the heroine, have become sought-after items in boutiques all over Turkey.

“We did not expect this,” Deniz Marsan, one of the fashion advisors for Ask-I Memnu told the news channel CNN-Turk. “Nothing like this has ever happened in Turkey before.”

Turks are passionate followers of home-made television soaps, some of which have been sold to Arab channels and have started to attract tourists from Arab countries who want to have a look at the places where their favourite series was filmed. But Ask-I Memnu, produced for Kanal D, a private channel, is a big hit even by Turkish standards.

Ask-I Memnu has not yet been sold to Arab stations.

The plot, a family saga set in today’s Turkey but based on a novel by Halid Ziya Usakligil from 1899, revolves around Adnan Ziyagil, a rich widower in Istanbul who marries the much younger and beautiful Bihter. Drama and intrigue set in as Bihter begins a relationship with Behlul Haznedar, her husband’s fun-seeking nephew.

Fans – and sponsors – will be sad when the saga, which has lasted two seasons, ends. “People even buy the perfume [of the main characters], even though they do not know how it smells,” said Handan Beynal, a shop assistant in an Istanbul perfume shop. “They see the bottles of a certain perfume brand in Ask-I Memnu, and they run out and buy them,” she said, shaking her head in disbelief.

Mrs Beynal and others said various other successful Turkish soap operas also had loyal followers and sometimes even pushed up demand for specific dresses or other items. “But never like this,” Mrs Yazili, the shop assistant, said about Ask-I Memnu.

Being a fan of the show can be expensive. The main female characters in the series wear exquisite clothes that are much more refined and high-priced than anything a normal Turkish woman would wear in every day life. Prices vary between 150 lira (Dh356) for a simple outfit to 9,000 lira for an evening gown, a substantial sum in a country with an average yearly income of roughly 14,300 lira per person.

But the makers of the soap insist that beautiful clothes and accessories are part of the escapist quality of the drama.

“We know that people do not dress like that in normal life,” Mrs Marsan, the fashion consultant, told CNN-Turk, which is part of the same media conglomerate as Kanal D. “But this is television. Everything is exaggerated – the mansion where they live, the make-up they are wearing. You will not see any dirt on the streets.”

For die-hard Ask-I Memnu fans, the suspension of disbelief is not a problem. “I run home every time to watch it,” said Gamze Zunbay, 29, a woman who confessed to being an Ask-I Memnu addict. “I would love to buy the clothes of Bihter, but I have not been able to find something suitable yet.”

Even if there will be no new season after the end of Ask-I Memnu this week, many Turks are certain that the next craze is just around the corner. “In Turkey, the soaps never end,” said Ozden Erol, a colleague of Mrs Yazili, the shop assistant. “Only the Arabs and the Turks are so crazy for soap operas.”

Mrs Erol said she was not a regular Ask-I Memnu follower herself, but she would definitely catch the final episode this Thursday. “Of course I will watch it,” she said with a smile. “Is there anyone who will not?”